DNA Flashcards
What is DNA, what does it stand for
a molecule that contains the genetic code that is unique to every individual
Deoxyribonucleic acid
What are the nucleotide bases? name them all
The DNA code is made up of very long chains of four basic building blocks (nucleotide bases) called Adenine (A), Guanine (G), Thymine (T) and Cytosine (C)
How many DNA in one chromosome?
A chromosome consists of one DNA chains running in opposite directions. The bases pair up to form the rungs of a ladder twisted to form a double helix
What are the pairing of bases
A + T
G + C
3 sub units of a nucleotide
Deoxyribose sugar
Phosphate group
Base
What does DNA carry?
the genetic instructions necessary for development, functions, growth and reproduction of all known organisms
What are chromosomes?
Long, thread-like structures made of a DNA molecule and proteins that carry genetic information
Where are chromosomes found?
nucleus of all body cells except for red bloods cells which don’t have a nucleus
How many chromosomes in the nucleus of body cells?
46 chromosomes contained in the nucleus of body cells
Of these, 23 came from the mother’s egg and 23 came from the father’s sperm
How are chromosomes numbered? and what are they called
from largest to smallest (1-22)
called autosomes
What are the sex chromosomes?
X and Y
Female have XX
Males have XY
What are genes?
a section of DNA that contains instructions for making proteins or controlling other genes
What are between genes?
segments of non-coding DNA
How many genes in the DNA of each person?
over 20, 000 genes
What do the genes and the non coding genes make up?
a person’s genome
What is DNA replication?
the process by which a cell copies its DNA before dividing, ensuring that each new daughter cell has a complete genome
What is interphase
the stage of the cell cycle when a cell grows, replicates its DNA, and prepares for cell division
Where does DNA replication happen?
In the nucleus, or the cytoplasm if there is no nucleus
When does DNA replication happen?
- Before a cell divide so that the new daughter cell can also get a copy of DNA
- It is before mitosis or meiosis
What are the 4 main enzyme in DNA replication?
Helicase (unzipping)
Primase (initialiser)
DNA polymerase (builer)
Ligase (gluer)
What does Helicase do?
- comes and unzips the two strands of DNA
- Breaks through the hydrogen bond that holds the DNA bases together
- You don’t want these strands to come back together, so SSB proteins (single stranded binding proteins) bind the DNA strands to keep them separated
What does Primase do?
- The DNA polymerase can’t figure out where to get started without a ‘primer’
- So the primase comes in and makes RNA primers on both strands so that the polymerase can know where to start
What does DNA polymerase do?
- Replicates DNA molecules to build a new strand of DNA
- They also have proofreading ability
- Only can build the new strand of DNA in the 5 prime to 3 prime direction
- 5’ to 3’ (top strand) is called the leading strand
- Bottom is called the lagging strand
- The DNA polymerase has to keep racing up to where the unwinding is happening because it can only go 5’ to 3’
What are the fragments in DNA replication called?
Okazaki fragments
What does ligase do?
Primers needs to get replaced with DNA bases but since the primers were made of RNA, Ligase (‘the gluer’) the takes care of the gaps between the the fragments sealing them together
What is a mutation
A mutation is simply a change to the nucleotide order/sequence in DNA
that can alter the genetic information within an organism, and can affect single nucleotides, larger sections of DNA or even whole chromosomes.
Mutations are the primary source of ________
genetic diversity
James Watson and Francis Crick- what? when?
- In 1953, Watson and Crick proposed the double helix model of DNA, describing it as two strands twisted around each other with complementary base pairing
- Their model explained how DNA could replicate and carry genetic information, forming the foundation of molecular biology
Marice Wilkins - what?
Wilkins worked on X-ray diffraction studies of DNA, which helped reveal its helical structure
His research and collaboration with Watson and Crick supported the double helix model, and he shared the 1962 Nobel Prize with them
